As an emotional experience jumping from an airplane for the first time can evoke whole lot of emotions wrapped into one. In my ten years of skydiving I’ve witnessed terror melded with ecstasy, excitement bonded to the facial expression of dread and just about every conceivable emotional combination in between. And somehow, in the end, every expression of the moment still seems to settle into an introspective smile that says, ever so gently, “I just did that… whoa”
So why do we do it? We do it for the freefall. There is no sensation equivalent to precisely controlling your body and it’s movements while simultaneously experiencing the sensation of floating. When we’re in freefall, we are flying. Combine that flying sensation with the freedom of cruising around the sky with friends, and you’ve got the makings of an excellent skydive.
Freefall is unbelievably gratifying… but why?
It’s all thanks to wind resistance and the ability of the human body, with practice, to balance on just about anything.
But how does it work? How is it that humans can take charge of their freefalling bodies and change their direction of movement and speed relative to their friends falling beside them?
When a skydiver exits an aircraft, the force of gravity begins to accelerate the body toward earth. This acceleration-force pulls the skydiver through the molecules in the air and forces the molecules to move around the falling body. In a perfect world the molecules would happily step aside and let the passing skydiver cruise on by. But we don’t live in a perfect world and it turns out that in order to move those air molecules they must be displaced, a process that takes time and creates a lot of drag. The air is resisting this rapid displacement and it’s an effect that’s referred to as wind resistance.
Since a skydiver is not in contact with an abrasive surface such as the ground and has very little friction to prevent the body from being moved while in freefall, they may manipulate their bodies by pushing against the wind resistance. Since every action produces a force equal and opposite that action, a skydiver literally pushes against the wind with a part of their body to have the wind “push back” and move them in a pre-calculated manner.
The same “push” against the wind resistance that a skydiver can use to move their body around can also be used to control their freefall speed. By exposing more of their body to the wind resistance, extending their arms, extending their legs or making their torso flatter, a skydiver can literally slow down their freefall. Or by doing the opposite and decreasing the amount of surface area they’ve presented, a skydiver can speed themselves up.
It’s takes a bit of practice to get all of your limbs working in unison and creating balanced movements to push against the air and maintain stability. A beginning jumper can maintain basic stability, move forward and turn left and right within about seven skydives.
Becoming more advanced and taking real multi-axis control of your body in the sky takes substantially more time and effort. Top-level skydivers train for years and accrue thousands of skydives to reach skill levels that allow true precision movements in freefall. I’ve posted a video example of what can be achieved by the human body in freefall after years of dedication.